Fluid pressure switch



March 3, 1964 J, GQNDEK 3,123,690

FLUID PRESSURE SWITCH Filed Feb. 19, 1962 INVENTOR J o HN 7. Go/vas/r BY Qw ATTORNEY United States Patent 3,123,690 FLUID PRESSURE SWITQH John T. Gondek, 2206 Roosevelt St. NE, Minneapolis, Minn. Filed Feb. 19, 1962, Ser. No. 174,997 6 Claims. (Cl. 20i)-82) This invention relates to an improvement in fluid pressure switch and deals particularly with a switch which may be operated by fluid under pressure and which is extremely accurate and dependable.

Various types of pressure operated switches have been previously produced. Most such switches are so constructed that there is a lag in the operation due to friction between the operating parts. As a result, the switch will not operate under all circumstances at the same pressure. It is an object of the present invention to provide a simple and effective switch which is extremely dependable in its operation, and which is extremely sensitive to variations in pressure.

A feature of the present invention resides in the provision of a pressure switch which includes an operating piston formed of extremely hard material such as anodized aluminum alloy. The piston is preferably freely guided for axial movement in a guide ring which may be formed.

A further feature of the present invention resides in the provision of a pivoted switch actuating arm which is interposed between the end of an adjustment spring and a pressure actuated piston. Due to the fact that the spring acts upon one side of this arm and the piston acts upon the opposite side thereof, the piston and spring being in axial alignment, the force of the piston and spring act idirectly through the arm and accordingly do not place any particular strain upon the pivot supporting the switch actuating arm. As a result, the effect of friction on the piston is greatly decreased.

A further feature the present invention lies in a simple and effective means connecting the piston to the switch operating arm. The piston as well as the switch operating arm is provided with a socket having a conically shaped depression or rounded axial cavity, the two cavities being substantially aligned. A pin having tapered ends is inserted between the two concave surfaces and acts as a means of transmitting pressure from one member to the other. With this arrangement, the slight pivotal movement of the switch operating arm does not create any particular problem in the transfer of pressure.

these and other objects and novel features of the present invention will be more clearly and fully set forth in the following specification and claims.

In the drawings forming a part of the specification:

FlGURE l is a sectional view through the switch showing the general arrangement of parts therein.

FIGURE 2 is an enlarged detail View of the switch operating piston and support.

The pressure switch A includes a housing 10 including a normally open side 11 which is closed by a closure plate 12. The closure plate 12 is held in place by cap screws 13 or other suitable fastening means, and a gasket 14 is preferably supported between the housing and the closure plate to form an effective seal.

The housing 10 is provided with a projecting sleeve 15 which is internally threaded, and which forms communication with the interior of the housing. An electrical switch 16 is mounted by suitable mounting bolts 17 within the housing it and includes a projecting plunger 19 by means of which the internal switch may be actuated.

The housing It) is provided with an elongated threaded aperture 2i) which leads from the exterior of the housing through a housing portion of increased thickness indicated at 21. An externally threaded screw 22 having an 3,123,690 Patented Mar. 3, 1964 2 axial socket 23 in its inner end is threaded into the passage 20. The socket 23 is designed to serve as a support for an adjusting spring 24, as will be later described.

The switch operating arm for operating the switch 16 comprises a bellcrank lever having an arm 26 engageable with the plunger 19 to operate the same, and including a relatively thick right angularly extending arm 27. The lever 25 is supported by a pivot 29 near the intersection between the two lever arms 26 and 27. The arm 27 is provided with an internally threaded aperture 30 extending therethrough. A set screw 31 having a conical depression 32 in its extremity is threaded into the aperture 30, and is held in adjustment by a lock nut 33.

As indicated in FIGURE 2 of the drawings, the spring 24 is provided with an end having convolutions 34 of relatively small diameter. The lock nut 33 is provided with a shoulder or flange of increased diameter which fits within the small dimeter end of the spring to hold the spring in alignment with t.e set screw 31. The tension of the spring 24 may be adjusted by threading the screw 22 inwardly or outwardly of the threaded aperture 20, a slot 36 being provided in the outer end to accommodate a screw driver or similar tool by means of which the position of the plunger may be adjusted.

As indicated in FIGURE 2 of the drawings, an aperture extends through the housing 10 in alignment with the internally threaded aperture 20 and includes portions of four different diameters. A relatively small diameter axial aperture 39 communicates with the interior of the housing 10. An aperture portion ll) of slightly larger diameter communicates with the outer end of the aperture portion 39. A portion 41 of still greater diameter communicates with the apertures 39 and 40, while the largest diameter portion 42 of the aperture extends the remaining distance through the housing It). The portion 4% of the aperture is designed to accommodate the piston 43 with a sliding fit. The piston 43 is provided with an axial socket 44 having a conical inner end. A concave disk 45 having a conical inner surface 46 is pressed against the base of the socket dd. The piston 43 is preferably formed of aluminum having an anodized or hardened surface while the bearing disk 45 is formed of steel or similar material to act as a hearing. A pin 47 having conical ends 49 is interposed between the socketed end 32 of the set screw 31 and the center of the bearing disk 45, the taper of the ends of the pin 47 providing clearance between the conical surface h: and one end of the pin and between the socket 325 and the opposite end of the pin. Thus only the extremities of the pin 47 engage the two bearing points.

A sleeve 50 of anodized aluminum or similar material is located in the portion 41 of the aperture to serve as a guide for the piston 43. A disk 51 of soft rubber or other similar resilient material is located in the portion 4-2 of the aperture, and it should be noted that there may be some clearance between the end of the sleeve 56 and the disk 51 so as to permit the rubber disk to bow downwardly the extent necessary to depress the piston. In view of the fact that it is only necessary for the piston 2-3 to move a few thousandths of an inch to operate the switch 16, only small clearance is necessary. A thin resilient disk 52 of Teflon or the like may overlie the rubber disk 51, and a sealing ring 53 of resilient material overlies the thin disk 52. When in use, the surface 54 of the housing lib is engaged against a cooperable surface, permitting the sealing 53 to form a seal between the two elements. The Teflon disk serves to protect the rubber disk from contact with fluids which might be injurious to the rubber.

In the operation of the apparatus, hydraulic fluid under pressure acts through the Teflon disk 52 to exert a pressure upon the resilient disk 51 tending to depress the piston 43. Pressure against the piston 43 is transmitted through the pin '47 to the socketed end of the set screw 31 which is threaded into the arm 2'7 of the bell crank lever 25.

The force against the piston 43 is'balanced by the spring which is adjustably supported by the socketed screw 22. The force of the spring is aligned with the force of the piston by the lock nut 33 which acts to center the reduced diameter end of the spring 24.

When the hydrauiic force against the piston 43 exceeds the force of the spring 24, the lever 25 is pivoted about its axis 29 to depress the operating lever i3 of the switch 16, the small amount required to operate the switch. As the operating lever 19 requires very slight movement to function, the angularity of the arm 27 of the lever 25 is insutficient to vary the opposing forces of the spring and piston.

In View of the fact that the spring 24 acts upon one side of the lever arm 27 and the piston driven pin 47 acts upon the opposite side thereof, only a very slight strain is exerted upon the pivot 29 supporting the lever 25. As a result, the lever may pivot very easily and the switch is extremely sensitive. The resilient disk and seal effectively prevent the leakage of fluid, and the pin 47 which acts between the piston. and the set screw transmits the pressure without appreciable friction.

In accordance with the patent statutes, I have described the principles of construction and operation of my improvement in pressure switches, and while I have endeavored to set forth the best embodiment thereof, I desire to have it understood that changes may be made Within the scope or" the following claims without departing from the spirit of my invention.

I claim:

1. A pressure switch including a housing including a cylinder providing communication between the interior and the exterior of said housing,

a piston s-lidably supported in said cylinder and subject to pressure entering from the exterior of said houss. spring supported within said housing in axial alignment with said piston, V V 7 bell crank lever having a pair of angularly related arms, one arm of which extends between said spring and said piston, V connector positioned between said piston and said one arm to transmit movement of said piston to said arm in axial alignment to said spring, whereby movement of said piston is transmitted through said arm to said spring,

12s as means pivotally connecting said housing to said bell crank lever at the juncture between said arms,

a switch mounted within said housing, and switch actuating means on said switch and in engagement with the other of aid arms for actuating said switch when said piston is forced toward said spring, said one 2mm and piston including opposed sockets, said con nector comprising a pin having tapered ends bearing against the bases of said secrets, said pin being free of engagement with the walls of said sockets.

2. The structure of claim 1 and including a resilient disk at an end of said cylinder externally or" said piston andthrough which pressure is applied to said piston.

3. The structure of claim 1 and including a sleeve providing the inner surface of said cylinder.

4. A pressure switch including,

a hollow housing having a pair of spaced parallel wall portions,

a cylinder in one of said wall portions and an axially aligned threaded aperture in the other of said wall portions,

a piston slidably supported in said cylinder and subject to pressure entering from the exterior of said houss. threaded member adjustably supported within said threaded aperture,

a bell crank lever having a pair of angularly arranged arms and pivotally supported by said housing with one 'arm extending between the axes of said piston and said threaded member,

a spring interposed between said threaded member md one side of said arm,

connecting means substantially axially aligned with said piston and extending between said piston and the other side of said arm, and

a switch element mounted within said housing and having a switch element actuating means engaging the other arm of said lever for actuation thereby upon movement of said piston.

5. The structure of claim 4 and including a plug of resilient material supported by said housing outwardly of said piston and through which the pressure is transmitted to said piston. V a

6. The structure of claim 4 and in which said connecting means includes a pin having tapered ends. 

1. A PRESSURE SWITCH INCLUDING A HOUSING INCLUDING A CYLINDER PROVIDING COMMUNICATION BETWEEN THE INTERIOR AND THE EXTERIOR OF SAID HOUSING, A PISTON SLIDABLY SUPPORTED IN SAID CYLINDER AND SUBJECT TO PRESSURE ENTERING FROM THE EXTERIOR OF SAID HOUSING, A SPRING SUPPORTED WITHIN SAID HOUSING IN AXIAL ALIGNMENT WITH SAID PISTON, A BELL CRANK LEVER HAVING A PAIR OF ANGULARLY RELATED ARMS, ONE ARM OF WHICH EXTENDS BETWEEN SAID SPRING AND SAID PISTON, A CONNECTOR POSITIONED BETWEEN SAID PISTON AND SAID ONE ARM TO TRANSMIT MOVEMENT OF SAID PISTON TO SAID ARM IN AXIAL ALIGNMENT TO SAID SPRING, WHEREBY MOVEMENT OF SAID PISTON IS TRANSMITTED THROUGH SAID ARM TO SAID SPRING, 